Most biological research activities on nitric oxide (NO) are using two chemical tools; arginine-based nitric oxide synthase (NOS) inhibitors and NO donor compounds. The majority of commercially available NO donors exhibit NO releasing capabilities by either spontaneous decomposition under physiological conditions or by metabolic transformations. A demanding task facing organic and medical chemists is how to incorporate such small molecule as NO into synthetically changeable structural moieties, and deliver nitric oxide, including its pharmacological equivalents and its redox derivatives, at the specific time and place to evoke biological functions. This proposed research project undertakes this challenge. The proposal stems from recent discoveries in No research that endogenous and exogenous S-nitrosothiol species are pharmacological equivalents of nitric oxide, which under certain conditions release nitric oxide (NO.) and its redox derivatives NO+ and NO-). The research plan is based recent findings in our laboratory that N- nitrosomine compounds such as substituted N-methyl-N-nitrosoanilines carry out protein S-nitrosation (NBO+ transfer reaction) in aqueous solution at neutral pH. The research program include two specific aims; 1. Design and synthesis of N-nitroso compounds which can release NO+, NO. and NO- under a variety of biologically relevant conditions. This includes; (a) design, synthesis and testing of three series of N-nitroso compounds with a wide range of transnitrosation potentials; (b) design, synthesis and testing of compounds in which a thiol or di-thiol group is tethered to the substituted N-nitroaniline moiety. These compounds act as NO. or NO- releasing agents through an intramolecular S-nitrosation upon activation. 2. Incorporation of the N-nitrosoaniline moiety into a peptide backbone and synthesis of specific S-nitrosating agents to inhibit papain, interleukin-1beta-converting enzyme (ICE) and protein tyrosine phosphatases (PTP). The long-term objective of this research program is to rationally design and synthesize a variety of nitric oxide (NO.) and its redox derivatives (NO+ and NO-) releasing reagents, and to investigate the interaction of these species with organic thiols and proteins. Our work is of benefit in biomedical research on the biology of nitric oxide and in pharmaceutical and clinic applications.